The invention relates to agricultural implements and more particularly to implements used for plowing under or burying stalks, roots and debris from row crops, such as cotton.
To control insect pests, such as the boll weevil and pink bollworm, all cotton stubble and debris must be plowed under after harvest. Several cotton-growing states have set deadline dates for this tillage to be accomplished.
Conventional tillage techniques are expensive and time consuming, usually requiring six or seven passes of machinery through the field. A typical tillage sequence is stalk shredding, disking, moldboard plowing, disking, land planing, and forming the new furrows. Due to the time required to accomplish these operations, winter rains often prevent cotton farmers from meeting the required legal plowing deadlines.
To reduce the cotton tillage requirements, several methods and machines have been developed. During the 1960's and 1970's, land grant universities and the United States Department of Agriculture Engineers developed methods of reworking existing cotton beds. These techniques involved stalk shredding, tearing the plant roots out of the beds with ripper shanks, and reforming the old beds.
Another method developed called for splitting the old beds in half and reforming new beds where the old furrows were.
Both of these techniques were utilized in the apparatus described in U.S. Pat. No. 4,131,163, entitled "Stubble Eradicating Implement," issued to Bezzerides on Dec. 26, 1978. Because these methods leave the crop debris on or near the soil surface, they have failed to achieve more than minimal acceptance with cotton farmers.
Another method is described in U.S. Pat. No. 4,779,684, entitled "Method and Apparatus for Extracting Plant Stalks and for Reshaping Beds," issued to Schultz on Oct. 25, 1988. This method utilizes a pair of converging coulter disks to grip and lift the cotton tap roots from the soil. After the tap roots are removed, the roots and shredded stalks are mulched into the surface layer of soil as the beds are reformed.
In this approach, the embedding of the debris is minimal, at best, leaving all of the debris on or near the soil surface. Pink bollworm pupae overwinter in cotton debris, and this shallow burial enables a high percentage of the pupae to survive and infest the next planting. Research has shown that the optional depth for survival of a pink bollworm pupae is two inches. On the surface, they will dry out or freeze. Buried deeper, they cannot emerge in the spring.
Still another technique is disclosed in U.S. Pat. No. 4,588,033, entitled "Cotton Root Cutter and Shredder," issued to Orthman on May 13, 1986. This technique utilizes a below ground cutting blade inclined diagonally across the plant row. The blade cooperates with an oppositely inclined above ground trash bar to uproot the cotton plants and deposit them on the ground transversely to the direction of travel of the apparatus. The uprooted plants are then picked up and shredded.
Again, as with the other techniques already discussed, this last technique leaves most of the crop debris on or near the soil surface.
Cotton debris often interferes with subsequent planting and cultivation operations; more importantly, unburied cotton debris serves as an overwintering site for pests, such as the pink bollworm. Recent research has shown that around 50% of pink bollworm moths emerging in the spring have overwintered in the crop debris. Deep burial of the debris will prevent most of these insects from emerging to infest the subsequent cotton crop.
Still another attempt at reduced cotton tillage techniques is to completely bury the debris. One such device is described in U.S. Pat. No. 4,350,207, entitled "Agricultural Implement for Extraction and Shredding of Stalks and Roots," issued to Ben-Dor on Sep. 21, 1982. This machine extracts the roots and stalks from the soil and shreds them in a shear-bar shredder. Using an optional subsoiler attachment, the shredded debris is buried into the soil from ten to twelve inches. A similar result is obtained by the approach of U.S. Pat. No. 4,856,597, entitled "Soil Working Machine," issued to Gal on Aug. 15, 1989.
Although both of these machines obtain the objective of burying the debris, the mechanical complexity required for each to operate is of such a level that keeping the machines operating is extremely difficult.
Still another method is a two-level plow with a scraper attachment as shown in U.S. Pat. No. 4,323,126, entitled "Ridge Mulch Tillage Method and Apparatus," issued to Stikeleather et al. on Apr. 6, 1982. In this type of device, a scraper attachment is used to deposit debris into the plow furrow. The debris is buried when the plow bottom turns over the adjacent crop row.
Cotton is a particularly difficult crop to handle and the plant is anchored by a long tap root. Cotton tap roots are difficult to sever and the debris does not fall into the furrow easily and, as such, much of the debris for the Stikeleather approach is left at or near the surface creating the same problems already noted for the prior devices.
It is clear from the foregoing that an efficient method and apparatus does not exist to embed or bury cotton debris.